1. Field of the Invention
The present invention relates to microorganism detection and sorting systems.
2. Prior Art
Most methods for the analysis of bacteria are based on the availability of a significant amount of biomass taken directly from plated growth media. Some direct methods, such as antigen-antibody agglutination reactions and deoxyribonucleic acid (DNA) hybridization reactions, target organisms in clinical specimens without growing them on plated media. Likewise, these methods require 1,000 to 10,000 organisms for positive reactions. The requirement for significant amounts of material in order to get a reaction, makes direct screening from environmental samples difficult due to the low concentrations of organisms. Recognition of 10-100 bacteria from an environmental sample requires ultra-critical sensitivity. This sensitivity must be built into a system in two ways, viz., in the signal generated from organism capture and in the instrumentation used to read that signal. Several such methods have been tried, and some have been successful, but these methods involve time-consuming preparative and analytical steps in large, sophisticated, laboratory-supported equipment.
A primary goal of this field device for microorganism detection, is to have recognition capability for 10 to 100 genetically engineered organisms per milliliter in environmental samples. Present identification methods are inadequate for three reasons: a large amount of biomass is required to identify organisms; the presence of more than one species cannot be determined without prior growth and isolation which takes 24-48 hours; and the characterization of genetically engineered organisms by biochemical profiles is meaningless, as these profiles can change with genetic manipulation. Thus, composite microorganism components such as DNA must be targeted, instead of the ability of the microorganism to ferment carbohydrates or use proteins.
Factors best targeted in genetically engineered microorganisms include those factors which endow them with special disease causing potential. Some examples include, the ability to colonize mammalian cells via specific attachment factors, the carriage of genes coding for the presence of pathogenic determinants, and cell wall components which play a part in pathogenesis of disease, produced by highly conserved regions of the DNA. Target approaches for these factors differ considerably from conventional identification schemes and, understandably, the methods for recognition of these factors must differ, especially since the targeted pathogenic factors are likely to be present in very small quantities.
The first signal should provide an indication of threat to rule in (or out) microorganisms found in one of four major classifications. This separation can be accomplished by filtration, cell sizing, or immunologic signal recognition. Groups to be separated include selected amoebae, selected yeasts, gram-negative and gram-positive bacteria, and single or double stranded RNA or DNA viruses.